Thread cutting taps for cutting circumferential threads into a cored to bored hole in a work piece are well known. The tap tool cuts a thread into the inside wall of a generally cylindrical hole, creating a female ridged surface which functions like a nut, wherein the ridge or land shape, heights and spacing and flutes there between normally follow one of several widely adopted thread standards. Taps are commonly available having a substantially cylindrical shank portion with a thread cutting portion on one end and a square drive head on the opposing end of the shank, although this configuration is not exclusively definitive. The thread cutting portion comprises a series of raised lands with flutes spaced between. The lands have hardened circumferential thread cutting portions formed thereon. The taps are available in various standard diameters, both english and metric (although also not limited to these), and are available having cutting thread portions configured to tap a bored hole with a thread according to national or international thread standards. For example, the American National Standards Institute (ANSI) has around a dozen different thread designations such as NPT or national pipe thread which is a U.S. standard for tapered threads, originally used to join steel or brass pipe and fittings. Other standards include M which is a metric screw thread compliant with ISO standards, several unified inch screw threads such as UNR for unified inch screw thread, UNRC which refers to the unified inch screw thread for coarse threads, among many others to numerous to name here. Similarly there are many ISO standard threads, some of which overlap the ANSI standards. To serve this need, tap tools are commonly available in standard body configurations for threading various standard diameter holes with various standard thread types.
The success of any tapping operation depends entirely on the use of the correct type tap together with proper hole preparation and having a tap drive means providing sufficient torque to form the threads within the bore wall, particularly into structurally hard components such as steel. As can be understood, the amount of torque required to tap the hole varies greatly based upon the material type being tapped, for example less torque is generally required to form threads into plastic materials than into steel. The torque is also affected by the quality of the tool used to ream the hole. Dull drills or reamers can work harden metallic surfaces thereby requiring additional torque to cut the threads with the tap tool. Also worn drills can result in undersized holes, again requiring additional torque to tap the hole.
Standard size taps of reasonable diameter are commonly driven by ‘T’ handle tap holders. Such tap holders receive the tap tool into an opening in the tool wherein the hole can be threaded with the tap by twisting the ‘T’ handle to drive the tap tool into the hole. Such conventional tap tools have drawbacks, however.
One drawback is that the conventional ‘T’ handle on a typical tap tool holder is of limited length, providing limited leverage for driving the tap into material. This limited leverage is problematic particularly in cases requiring substantial torque to twist the tap into the hole to cut the threads. Required torque is further aggravated by the hole and tool conditions outlined above and is also higher when the material being tap threaded is a hard material such as steel.
Another drawback of conventional ‘T’ handle tap tool holders is that the arms of the ‘T’ handle prevent the tapping of hole which is located near any obstacle or obstruction that would prevent the ‘T’ handle from rotating freely, such as when the hole is near a wall or other nearby obstruction.
Therefore, a tool for tapping a hole that overcomes the limitation of the prior art, that provides a means of applying additional torque to the tap for cutting threads into hard materials, a tool that accepts a variety of standard diameter and thread type taps, a tool that is configured to be driven by a standard socket set socket and ratchet drive without purchasing a special purpose driver, such a ratchet driven tool for tapping a hole would be useful and novel.